1. Field of the Invention
The present invention relates to an apparatus for decoding compressed image data, and more particularly, to an apparatus for decoding compressed image data which is variable length coded to be recorded or transmitted in a format having a fixed area, macroblock remainder (MR) data and video segment remainder (VR) data. The present invention is based on Korean Application No. 96-41389, which is incorporated herein by reference.
2. Description of the Related Arts
In a digital video cassette recorder, one frame of a picture is divided into a plurality of segments, and each segment is divided into five macroblocks. Also, each macroblock includes four DCT blocks for a luminance signal and two DCT blocks for a color difference signal.
A code whose length exceeds the length of the specified fixed area as a result of the variable length coding is called a macroblock remainder (MR). The MR is recorded in the blank area of another DCT block which belongs to the same macroblock. Data remaining after being recorded in the blank area of the other DCT block is video segment remainder (VR) data. The VR data is recorded in the blank area of another macroblock which belongs to the same segment. Any code remaining after being recorded in the blank area of the other macroblock is thrown away. This is because a video segment whose length is fixed is processed independently of other segments during the coding.
During the decoding of compressed data of the video segment unit recorded as described above, fixed data of a DCT block unit is completely decoded first. Then, any existing MR data and VR data are decoded.
However, in a general decoding apparatus, two memories for storing compressed data to be decoded are required so that data of a segment unit being processed is stored in one memory and data of a segment unit to be processed next is stored in the other memory. Since two segment memories are used, hardware costs are increased.